We've discovered evidence of just about every gas imaginable out in space, but one we'd never seen was molecular oxygen, the stuff we breathe everyday. Now, thanks to powerful infrared telescopes, we've found the very first traces of space oxygen.
While individual oxygen atoms are found throughout space, that's not what we breathe. Instead, we inhale O2, which is a molecule composed of two oxygen atoms bonded together. This particular gas is very common on Earth - it accounts for about 20% of the air around us - but we had never found molecular oxygen in space... until now.
The key to the gas's discovery was the Herschel Space Observatory, which is tasked with exploring the infrared wavelengths of the universe. This allows it to see the coldest and dustiest parts of the cosmos. In the case of molecular oxygen, that's a very good thing, as researchers believe the gas was locked up in the frozen water ice that surrounds tiny dust grains.
The telescope then detected the oxygen gas in the vicinity of the Orion Nebula, where it's thought that starlight was able to first warm up the ice and then break it into its constituent atoms. The now-free oxygen atoms were then combined into molecular gas. NASA researchers still believe that this molecular oxygen is abundant in the universe, even if the evidence for it remains strangely lacking. Now that we have some idea where to look, though, it may be easier to find more.
Herschel project scientist Paul Goldsmith explains:
"Oxygen gas was discovered in the 1770s, but it's taken us more than 230 years to finally say with certainty that this very simple molecule exists in space. This explains where some of the oxygen might be hiding," said Goldsmith. "But we didn't find large amounts of it, and still don't understand what is so special about the spots where we find it. The universe still holds many secrets."